1. Field of the Invention
The present invention relates to method and apparatus for breaking optical fibers and, more particularly, to method and apparatus especially for breaking optical fibers which include large cores having varying boundary layer stresses therein.
2. Description of the Prior Art
A desirable condition in breaking an optical fiber is the production of a flat end surface. Such a flat end surface is essential to the fabrication of a low loss splice.
The article "Optical Fiber Joining Technique" by D. L. Bisbee in the Bell System Technical Journal, Vol. 50, No. 10, dated December 1971, at pages 3153-3154, describes a method for breaking optical fibers comprising the following sequential steps: laying a fiber across a sharp metallic edge; positioning a Tesla coil so that its discharge is concentrated at the point where the fiber touches the metal to score the fiber; and breaking the fiber by pulling or bending it.
Another technique is disclosed in the article "Optical Fiber End Preparation for Low-Loss Splices" by D. Gloge, P. W. Smith, D. L. Bisbee, and E. L. Chinnock in the Bell System Technical Journal, Vol. 52, No. 9, dated November 1973, at pages 1582-1584. There, a fiber is clamped, the free end thereof is draped over a bridge-like structure in the area of the intended break, and the free end is attached to a gauge to monitor the level of the applied tension. When the fiber is scored in the area of the bridge-like structure, the applied tension causes the fiber to break.
Prior art methods, however, were found not to be adaptable for consistantly producing flat ends when breaking large diameter Sodium Germanium-doped or similar type fibers, because such fibers include large cores having varying boundary layer stresses therein which are introduced by the fiber manufacturing techniques used. The problem, therefore, remaining is to provide a method for breaking optical fibers including large cores having varying boundary layer stresses therein.